1. Field of the Invention
The present invention relates to a mounting structure of a ball grid array type IC which has a plurality of solder balls provided on a bottom surface of its body portion so that the ball grid array type IC can be mounted on a board.
2. Description of the Related Art
A first structure according to the related art is shown in FIGS. 7A, 7B, and 7C. The first structure includes: through-holes 103 formed in at least two corners of a substrate 102 of a semiconductor package 101; and reinforcing leads 106 inserted into the through-holes 103 of the semiconductor package 101 and into through-holes 108 of a mounting board 107 to fix the semiconductor package 101 and the mounting board 107 to each other surely after the semiconductor package 101 is mounted on the mounting board 107 (e.g., see Japanese Patent No. 3,183,278).
In the first structure, the reinforcing leads 106, which are provided as separate elements after the mounting of the semiconductor package 101 on the mounting board 107 in order to reinforce the mounting of the semiconductor package 101 on the mounting board 107, are soldered to the mounting board 107 to prevent the semiconductor package 101 from peeling off after the mounting.
A second structure according to the related art is shown in FIGS. 8A, 8B, and 8C. The second structure includes: a BGA package 202; a plurality of BGA terminals 221 provided on one surface side of the BGA package 202; solder balls 204 formed on the plurality of BGA terminals 221; a plurality of BGA protrusions 203 which are provided on the same surface side as the BGA terminals 221 and each of which has a step protrusion portion 232 in its middle, and a conical protrusion portion 231 extending to its tip; a printed board 201; a plurality of BGA connection terminals 211 which are provided on one surface side of the printed board 201 and which come into contact with the plurality of solder balls 204 on the BGA package 202; and BGA protrusion-inserting holes 205 which are provided on the same surface side as the BGA connection terminals 211 and in which the BGA protrusions 203 having the step protrusion portions 232 on the BGA package 202 are inserted (e.g., see JP-A-2002-246512).
In the second structure, there is however a problem that the BGA protrusions 203 are apt to come out after the BGA protrusions 203 are inserted in the BGA protrusion-inserting holes 205 of the printed board 201. In addition, since the BGA protrusions 203 are provided on four corners of a bottom surface of the BGA package 202, orientation of the BGA package 202 cannot be decided when the BGA package 202 is mounted on the printed board 201. Accordingly, there is a problem that the BGA package 202 is apt to be mounted in an incorrect direction.